MEP 804 - Over Voltage

[Fmeroney]

Hey all,
I did a voltage check today after a routine startup and noticed that it’s was producing 132v so I tried to turn it down, as i turned it down the voltage spiked to 170+ volts and the unit shut of. I then attempted to do the same on restart but got the same results.

Can someone point me in a direction on where to find the issue? Thanks in advance.


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[Chainbreaker]

Just a thought...sometimes those type of wiper switches get dirty/oxidized from lack of movement. With the unit turned OFF, I would mark where it was last set for 120 V and then fully exercise the switch fully stop-to-stop both directions several times and then return to the mark.

Then restart and see what it is reading and try adjusting it for proper voltage. If the problem still exists you have something wrong elsewhere.

Have you downloaded the Technical Manuals for it located here on SS?

 

[Guyfang]

You do have the QUAD MWO on this set, right. And the MOV?

 

[Fmeroney]

Just a thought...sometimes those type of wiper switches get dirty/oxidized from lack of movement. With the unit turned OFF, I would mark where it was last set for 120 V and then fully exercise the switch fully stop-to-stop both directions several times and then return to the mark.

Then restart and see what it is reading and try adjusting it for proper voltage. If the problem still exists you have something wrong elsewhere.

Have you downloaded the Technical Manuals for it located here on SS?

I do have all the TMs for the 804, and I will give that a try and see what happens.


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[Fmeroney]

You do have the QUAD MWO on this set, right. And the MOV?

Hi Guy,
I’m not sure What a Quad MWO or MOV are... can you elaborate?

Thanks,
Frank


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[Zed254]

TB 11-6115-741-24, page 33 of 136 in the pdf file. Here's this TB - https://www.steelsoldiers.com/threads/military-mep-generator-reset-information.169771/

Search the Technical Bulletin for details on your machine for the Quad fuse install. I referenced the 805 above (from another thread).....and your 804 is on the same page....very similar machine to the 805a.

 

[Fmeroney]

TB 11-6115-741-24, page 33 of 136 in the pdf file. Here's this TB - https://www.steelsoldiers.com/threads/military-mep-generator-reset-information.169771/

Search the Technical Bulletin for details on your machine for the Quad fuse install. I referenced the 805 above (from another thread).....and your 804 is on the same page....very similar machine to the 805a.

Thanks for this, looks like my machine needs the fuse installed. I ordered the parts, do you think this could be linked to my issue?


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[kloppk]

It's not related to the quad mod. That mod just protects the Quad winding from getting damaged should the voltage regulator fail. The MOV mod helps protect the voltage regulator from failing due to voltage spikes from the quad winding causing the diodes in the regulator to short out.
When I was at your place a while back I saw the same issue with your output voltage being high and trying to adjust it making it jump around. I recall letting you know about it and the coolant "leak" when I was there.

 

[Fmeroney]

It's not related to the quad mod. That mod just protects the Quad winding from getting damaged should the voltage regulator fail. The MOV mod helps protect the voltage regulator from failing due to voltage spikes from the quad winding causing the diodes in the regulator to short out.
When I was at your place a while back I saw the same issue with your output voltage being high and trying to adjust it making it jump around. I recall letting you know about it and the coolant "leak" when I was there.

I remember, fixed the leak but haven’t been able to locate the source of the over voltage issue...


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[smokem joe]

With the machine off spray deoxit in that control and exercise it fully from one extreme to the other. You'd be surprised what cleaning the contacts can do

 

[Fmeroney]

With the machine off spray deoxit in that control and exercise it fully from one extreme to the other. You'd be surprised what cleaning the contacts can do

I’ll give it a go!


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[Guyfang]

But FIRST the Quad MWO. If the volt reg is bad, and is shooting over voltage into your main gen, at some point, the exciter coil will go south for the winter.

 

[Fmeroney]

But FIRST the Quad MWO. If the volt reg is bad, and is shooting over voltage into your main gen, at some point, the exciter coil will go south for the winter.

Will do, got the parts on order and will not fire it up till I have that in.


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[Light in the Dark]

Get some deoxit contact cleaner and go through all of the switches and contacts while you are waiting for the mod parts to come in. I have experienced over voltage readings on 803s from corrosion, that disappear after everything is cleaned up.

 

[Fmeroney]

Get some deoxit contact cleaner and go through all of the switches and contacts while you are waiting for the mod parts to come in. I have experienced over voltage readings on 803s from corrosion, that disappear after everything is cleaned up.

Deoxit came tonight so I’m gonna hit it tomorrow!


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[Light in the Dark]

In the future if you have any Guitar Center locations near you, they normally stock the stuff.

 

[Jackb379]

Did this fix your issue ? I’m having a similar issue?